NSA deeply involved in US drone strikes: report

America's National Security Agency (NSA) is deeply involved in US drone strikes against Al Qaeda militants, using electronic surveillance tools to track down terror suspects, according to a newspaper report.

The Washington Post report was based on documents provided by Edward Snowden, the US intelligence contractor-turned-leaker who has exposed the massive scale of the NSA's eavesdropping efforts.

The NSA, which spies on electronic communications of all kinds and protects US government communications, has been one of the most secretive of all US intelligence outfits.

Its employees used to joke that NSA stood for either "No Such Agency" or "Never Say Anything."

The operation was made possible in part by an email from Ghul's wife that was scooped up by the National Security Agency's vast surveillance dragnet, it said.

The United States has never publicly confirmed that it took out Ghul, but documents passed to the Post by Snowden made clear he was killed by the US government last year.

Ghul was captured in 2004 and under questioning helped reveal Osama bin Laden's courier network - information that eventually led to the US commando raid that killed the Al Qaeda mastermind.

Ghul spent two years at a secret CIA prison, and in 2006 the United States transferred him back to his native Pakistan, where he was released and returned to Al Qaeda.

To help the CIA locate Ghul and other terror suspects, the NSA placed "a surveillance blanket over dozens of square miles of northwest Pakistan" to uncover communications and the whereabouts of Al Qaeda militants, the newspaper said.

The email from Ghul's wife "about her current living conditions" included enough details to confirm the coordinates of their home, according to a document leaked by Snowden.

"This information enabled a capture/kill operation against an individual believed to be Hassan Ghul on October 1," said the document quoted by the Post.

The newspaper said it was withholding numerous details about the "targeted killing" missions at the request of intelligence officials who were concerned about possible damage to operations and national security.

As with previous leaks from Snowden, the NSA did not deny the report but issued a statement saying its spying was focused on suspected terrorists and other threats to the United States.

"Our activities are directed against valid foreign intelligence targets in response to requirements from US leaders in order to protect the nation and its interests from threats such as terrorism and the proliferation of weapons of mass destruction."

The drone bombing campaign, president Barack Obama's primary tactic against Al Qaeda, has been portrayed as a purely CIA undertaking.

But the Post report showed the country's eavesdropping agency has played a crucial role in providing "signals intelligence" to the CIA for the controversial drone strikes.

The NSA also created a clandestine unit known as the Counter-Terrorism Mission Aligned Cell, or CT MAC, to focus spying resources on elusive terror suspects.

Snowden, who has portrayed himself as a whistleblower, is wanted by US authorities on espionage charge but he has secured asylum in Russia.

NSA chief, top deputy expected to depart soon

The director of the NSA and his deputy are expected to depart in the coming months, US officials said on Wednesday, in a development that could give Mr Obama a chance to reshape the eavesdropping agency.

Army general Keith Alexander's eight-year tenure was rocked this year by revelations contained in documents leaked by Snowden about the agency's widespread scooping up of telephone, email and social-media data.

General Alexander has formalized plans to leave by next March or April, while his civilian deputy, John "Chris" Inglis, is due to retire by year's end, according to US officials who spoke on condition of anonymity.

One leading candidate to replace Alexander is vice admiral Michael Rogers, currently commander of the US Navy's 10th Fleet and US Fleet Cyber Command, officials said.

The 10th Fleet and Fleet Cyber Command both have their headquarters at Fort Meade, Maryland, between Washington and Baltimore. The NSA is also headquartered at Fort Meade.

NSA spokeswoman Vanee Vines said Alexander planned to leave office in the spring after three extensions to his tenure, and the process for picking his successor was still under way.

"This has nothing to do with media leaks, the decision for his retirement was made prior; an agreement was made with the [secretary of defence] and the chairman for one more year - to March 2014," she said in an email.